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At least 37 records · Page 2Linked to original sources
PubMed1986

[Experiences with the implantation of a multichannel electrode in the acoustic nerve].

The authors developed a surgical approach to the acoustic nerve enabling the introduction of an electrode into the acoustic nerve. A multichannel electrode was implanted by this method in a deaf patient. The receiver casing for percutaneous transmission was fixed in the mastoid. Encouraging hearing results were obtained over a period of two months by electrical stimulation of the acoustic nerve.

Auditory Perception↗
PubMed1980

Changes of acoustic nerve and cochlear nucleus evoked potentials due to repetitive stimulation.

Evoked potential recordings were studied in the acoustic nerve and cochlear nucleus of adult decerebrate cats as a function of the tone duration (1-1500 msec) and the tone repetition rate (0.5/sec-200/sec). Response decrements due to repetitive tonal stimulation were primarily a function of the inter-tone interval. At inter-tone intervals longer than 100 msec, no response decrements were observed in the acoustic nerve or the cochlear nucleus. With shorter inter-tone intervals, reversible response decrements of identical magnitudes ocurred in both the acoustic nerve and the cochlear nucleus evoked potentials. The mechanism of response decrement may be due to depression at the hair cell-acoustic nerve junction.

Acoustic Stimulation↗
PubMed1993

Malignant nerve sheath tumor with rhabdomyoblastic differentiation arising from the acoustic nerve.

A case of a malignant nerve sheath tumor with rhabdomyoblastic differentiation arising from the acoustic nerve in a 38 year old man is reported. At autopsy, the tumor was found to be extensively involved in the right cerebellopontine angle of the brain stem. Histologically, the tumor was composed mainly of spindle-shaped tumor cells proliferating in hypercellular fascicles scattered with pleomorphic cells. The tumor cells were characterized by high mitotic activity and invasive growth. Occasional tumor cells had eosinophilic cytoplasm, which in a few cases was cross-striated. Cytoplasmic interdigitations and a thick basal lamina were confirmed ultrastructurally. Immunohistochemical analysis revealed that some tumor cells were positive for myoglobin and desmin, but weakly positive or negative for S-100 protein. The patient did not have von Recklinghausen's disease.

Adult↗
PubMed1994

Facial and acoustic nerve preservation during excision of extracanalicular acoustic neuromas using the suboccipital approach.

The results are presented from a consecutive operative series of 62 acoustic neuromas in 60 patients following the introduction of improved neurophysiological monitoring techniques. Twenty-two patients had usable preoperative hearing. Thirty tumours were less than 2.5 cm diameter and 32 greater in size. Operation was via a 3-4-cm diameter retromastoid craniectomy. The internal auditory meatus was opened by an ENT surgeon (RM) using a drill and the facial nerve identified by stimulation. The tumour was then centrally evacuated by a neurosurgeon (MT/HC) using an ultrasonic aspirator, and the thin exterior part of the tumour carefully dissected off the nerves in or around the capsule with constant stimulation and monitoring of facial EMG, BSAEP and electrocochleography. A new type of stimulation probe has been designed and coupled to a stimulator/integrator/tone burst generator (SB) so that continuous immediate direct feedback to the surgeon is possible. A variable amplitude discriminator rejects baseline EMG (> 50 microV) and a gating circuit prevents stimulus artefact (during monopolar stimulation) from causing interference. By these means the VII nerve could be identified even when translucent and undefinable as a nerve bundle. Anatomical preservation was possible in 98% of VII nerves. Full facial function was present in 20 cases immediately postoperatively. Full delayed recovery occurred in 23 cases giving an eventual total in House Grade I of 69%. Seven other cases recovered to House Grade II. There was therefore 81% satisfactory facial nerve function. This percentage is exactly the same for larger and for smaller tumours. Anatomical preservation of the VIII nerve was achieved in 24/62 (39%) of the whole series and 11/16 (69%) of those with a hearing loss of < 50 dB. Functional preservation of hearing described as usable by the patient (< 65 dB) was achieved in 7/22 cases (32%), 3/13 (23%) in tumours < 2.5 cm and 4/9 (44%) in those > 2.5 cm diameter. Hearing preservation of < 50 dB in patients with preoperative hearing threshold < 50 dB and tumours of < 2.5 cm was 3/11 (27%). Monitoring by BSAEP and ECochG was technically unsatisfactory because the responses were affected by drilling and stimulation. Acoustic nerve preservation should be attempted in all cases with measurable hearing, regardless of tumour size.

Ear Neoplasms↗
PubMed1992

[Microsurgical anatomy of the region near the porus acusticus internus; arteries around the facial and acoustic nerves bundle].

The microsurgical anatomy of the cerebellopontine cistern around the porus acusticus was studied under the surgical microscope, using the heads of 20 cadavers. The relationships among the porus acusticus, facial and acoustic nerves, and neighboring arteries were noted carefully. The arteries were the meatal loop of the cerebellar artery, the internal auditory artery (I.A.A.), the subarcuate artery (S.A.), and the perforating artery (P. A.). The cerebellar arteries made the meatal loop and the arterial-nerve complex while they passed in front of the porus acusticus. Most of the cerebellar arteries were the main or rostral trunk of the AICA. The I.A.A. supplying the facial and acoustic nerves usually originated from the meatal segment of the cerebellar artery and ran into the anterior part of the porus acusticus to enter the internal auditory canal. The S. A. penetrating the subarcuate fossa made a common trunk with I. A. A. or branched from the cerebellosubarcuate artery. One recurrent P. A., a special type of the P. A., was usually present on each side. Since the artery ran between the nerve bundles of the facial and acoustic nerves, it could not be seen through the lateral suboccipital approach.

Arteries↗
PubMed1999

[Minor functional disorders after surgery of acoustic nerve neuroma].

UNLABELLED: Acoustic neuromas must be removed surgically, otherwise serious complications may occur. Removal of an acoustic neuroma most often leads to disorders of balance, hearing, and sometimes facial motor function. Many earlier studies have approached the hearing and facial motor function. However, the facial nerve also comprises sensory and secretory fibers which, when injured, may produce minor disorders affecting patient's quality of life. The purpose of this work was to evaluate the quality of life, secretory and taste disorders after acoustic neuroma surgery. PATIENTS AND METHOD: Among patients operated on between May 1985 and May 1996, we selected only those who presented a normal facial function 3 months after surgery. We thus selected 93 patients and sent them a questionnaire in December 1997. We received 74 answers. RESULTS: The period between the operation and the dispatch of the questionnaire was on an average 5.5 years (range 19 months-12 years 9 months). Impairment of quality of life was frequent (59% of cases), and changing way of life less so (30%). 74% of the patients described balance disorders. One-quarter of the patients indicated they experienced disorders of facial mobility. Only 3 patients had no disorder. CONCLUSION: Secretory and taste disorders are frequent after neuroma surgery. Despite their mildness, patients should be advised accordingly because of possible impact on quality of life. This study also points out the lack of precision in the estimation of facial mobility. A better evaluation of patient complaints would be useful.

Adult↗